The invention relates to a starter for an internal combustion engine. By way of example, one such starter is described in the “Kraftfahrttechnisches Taschenbuch”, a book on motor transport technology issued by the Robert Bosch Corporation, 25th edition, p. 986, in the form of a pre-engaged Bendix starter, which is actuated via a so-called pull-in relay. This relay carries out the pulling-in functions, that is to say meshing the pinion of the starter motor into the ring gear of an internal combustion engine and switching the main current of the starter motor. When meshing the pinion into the ring gear, a tooth of said pinion can strike against a tooth of said ring gear, which is why the engagement process is assisted by a meshing spring. This starter design, which is known from prior art, admittedly requires only a single relay and can therefore be produced at relatively low cost, but on the other hand it results in very difficult working conditions for the process of meshing said starter pinion into said ring gear and for the switching process for the high motor current. Working conditions are particularly difficult in this embodiment of the switching device for the main current of the starter, the maximum possible torque of which is already produced during start-up from rest. If the pinion of the starter motor is not thereby completely engaged into the ring gear of the internal combustion engine, at the least inadmissibly large loads on the toothing of the ring gear can occur over the service life of the starter. This gives rise to the danger of one or a plurality of teeth breaking off.
In order to improve the process of meshing a starter pinion into a ring gear of an internal combustion engine, particularly in the case of high-power starters, it is furthermore known from the aforementioned reference for the motor current to be switched on in two stages in so-called pre-engaged starters. In a first stage, the pinion of the starter is moved against the ring gear of the engine and the armature of the starter motor is at the same time fed with a reduced current; thus enabling said armature and, with it, said starter pinion to rotate when meshing into said ring gear. In so doing, the meshing process is made easier. The meshing mechanism is in this case provided with a ratchet, which only at the end of the process of meshing the starter pinion closes a further switching contact of the relay and via said contact closes the main current circuit of the motor. As a result, the meshing process and the switching of the main current of the motor can take place in two separate operating stages; however, the design of the pull-in relay is thereby more complicated and more susceptible to defects from the mechanical and electrical points of view. The main current of the starter motor is, however, likewise powered up in one switching operation; thus enabling the maximum torque of the starter to already be present at the pinon/gear ring interface while the internal combustion engine with its large mass is still at rest.